Jeez, I didn't think that saying I thought the trident seal was sensitive constituted "railing" but everything I've been told about it said they were easy to break.

I anneal my ring tests overnight since I am seldom in a hurry. Factory floor tests are pretty much what Skeels was doing..

I also still use my dilatometer, all of the time since it tells me where in the ballpark I am. If a ring sample or a trident seal breaks, you don't know anything. Los Alamos Labs assured me that regardless of the modest cost of my unit, that it is quite accurate when tested against their big kids toys. I would admit that when I turn it over to the inexperienced, strange things happen. I believe that Corning will also say that any tests that you do there should be performed by the same person.

Ring tests really speak to you the moment you put them in the diamond saw. 99 times out of 100, if you saw it, it breaks right away if it is strained. For that, you need no polariscope but then again you don't know which side of the expansion viscosity curve you were on the wrong side of either. The more tools you use, the better off you are. I would say that since I got rid of my "Help", I have never had a complaint about a rod or a frit not fitting SP87. or other comparable soda lime glasses.

What I have gotten out of this thread, and I greatly appreciate it, is the need to pay a lot more attention to the annealing point as determined by the spreadsheet as well as physically measuring it . It's also nice to see John Croucher surface after some time in the shadows.

It’s great to see John Croucher here. I was hoping he’d show up. And now that he’s here:

John, I understand the problems color bar makers have in being unable to control the melt and therefore the predictability/quality of each studio’s clear furnace glass, but it’s not like there was ever a “standard” – in-house or otherwise – in the kiln-glass world. When Bullseye developed its first line of Tested Compatible glasses, there was no standard either. We had to develop one. We called it “Tested Compatible” - not “90 COE” – and published the test so that anyone could do it. We created and stockpiled a clear standard T-glass for testing. I’d also like to add that the “fused glass manufacturers” (plural) you refer to didn’t exist at that time. We were alone – for a good decade at the start. It wasn’t until one other manufacturer came into the market and wanted to match Bullseye without saying “Compatible to Bullseye”, that the term “Tested Compatible to 90.0 COE” came into the market.

I’m not sure I understand why you say there was no “standard” in the blowing market when you entered, but then say that SP87 was the standard and that you matched that with your own batch. So why not have just called it Tested to Match SP87 rather than having to deal with all this confusion about COEs, which you agree don’t guarantee compatibility?

I know that we all make decisions based on marketing and the interests of being user-friendly, but if those decisions screw with the user’s understanding of the product and process, I’m not sure whether we’re helping ourselves.

(On the other hand, I am regularly reminded by wiser minds in the marketing dept at BE that the Republicans won our last election by having simplistic one-liners and that the Democrats - who thought giving people lots of detail would bring them to intelligent conclusions - LOST)

Finally, I do very sincerely appreciate your willingness to speak publicly on these issues. It is refreshing to find a manufacturer who will come out from behind a website or their marketing literature. And it is undeniable that what Gaffer brought to the studio glass scene was color bar that is controlled to much higher tolerances than the previously existing products. We’ve done some limited testing on rods and “96” sheet glass in our factory and our (again, limited) results show the Gaffer to be MUCH tighter within its own range (not, necessarily in matching a "96" sheet) than any of the other color bar lines we’ve tested.

So. Speaking of compatibility ranges: What is the number of degrees of angle of retardation high and low that Gaffer accepts, i.e., the actual readings on your polarimeter?

Bullseye, for instance, accepts the range between 4 degrees high and 2 degrees low.

Again, thanks for the appearance. (And I apologize for the “full court press” that Jim and I put on you down in Perth 2 years ago – the Pinot made us do it)

when you say "tested compatible" it doesn't give the user any information about it's relationship to other products out there. "96" does say something about the relationship to other products and most glass people are interested in that relationship. While it is true that some products in the 96 L.E.C. range don't fit other products in the same range, the vast number of them do. That in itself is pretty useful to know. The inconsistencies come when fitting transparent glasses to opaques since they really have radically different structures. Both systems have seemed to co-exist for some time with some incompatibility, but not really that much when you look at the great variety of products offered up to the consumer.

I think John refers to Spruce Pine as the standard in that it was first in the commercial batch community and had a big market share by the time upstart companies like gaffer came along. While it would have been better if SP had not had such a high expansion in my thoughts, it isn't going to change anymore than bullseye is going to suddenly move it's expansion and viscosity either. It is what it is. The choice for a color manufacturer is to adapt to as wide a market as possible or to suffer the consequences of isolation. I forget which of the upstart batch companies decided to make a 93 expansion a few years back making the argument that it wanted to separate itself from the crowd. The stuff fit nothing well at all and was quite short lived.

Language is language based on common usage. Look at the term Dichroic Glass. It isn't dichroic glass at all based on the true definition. Try to get people to stop calling CBS "Dichroic".

When you take the group that won't even melt a batch glass at all and insist on fenton cullets you have yet another glass that is away from the mainstream. It fits little comercial color well at all. People buy lots of it.

In the Netherlands in the 60th there was a scene of artists using flat glass from England Germany or France, fusing colours together, adding potash between sheets for volcano effects and at the end holding it all together with the newly developed acrylic and epoxy based glues. Things cracked and empirical experience was developed, hot forming was done in bell type kilns with big open gas flames, very uncontrolled annealing but in the end it was all glued together. Until after 20 years the glue falls apart.
Rods in the blown glass scene where used by factory's well before we where born and with enough knowledge to do the ring test and adjust or even the tests measured on the polarimeter according to the Philips method.
I know Orrefors used to make Kugler hold a melt, get a sample to test on the polarimeter and if it was close enough buy the whole melt.
We at the academy in the 70th, where stuck with cullet from the automated gobbletery at Leerdam, new which colours fit. The cullet was our constant and we knew about the ring and cane tests. Now non of the students have a clue.
Some studio people in the 70th batched themselves but all with links to helpful engineers in the glass industry.
Otherwise it was Harvey's Glassblowing with Erwin's recipes and Frank Kulasiewicz book apart from Sholes and Weyl.
My father started to hand out photocopies of the fascinating "receptbuch fur die praktische Glasschmelzer" by Schmidt to all the interested visitors, I used the book in the early 70th to melt colours at the academy in the colour pot furnace we build knowing vaguely about expansion and ways to make things fit together. Got a hold of S. Simmingskold Ravaror for glassmaltning (Published in 1963) in 1973 while I was at Orrefors. With an add for Polarizing microscopes but no mention of expansions.
Later on in the 70th we got a copy of internal educational material from Philips with very detailed and up to date information on the chemical and physical properties of glass.
Still we used the cullet available to the academy for free.
Pelletised batch came into the picture much later. In the early 80th I did extensive tests for Rhone-Poulenc with their "CRISVER route" material developed by Mr. Richard. An alkaline silicate was made to react with metallic nitrates in water or an organic solvent. The result is a precipitate of organic oxides and by product alkaline nitrate, which is filtered off. During synthesis, these oxides take up the same arrangement, as they will have in the vitreous state. Consequently, such melts vitrify faster and at lower temperatures than traditional compositions. Or so it seemed. One way to try find new markets for their water glass.
Philips started to develop a plant for palletizing there base of hundreds of special glasses that they would melt only a few times a year in there glass factory " Philips Lighting" build in 1980 in Winschoten.
It was not until 10 years later that they started to make there batching facility available to outsiders and market a few basic batches available like a 24% PbO glass with in the tech. info viscosity info and average expansion coefficients:
25-300: 9.35
25-400: 9,65
And an annealing curve.
For the "studio glass" scene they developed a lead-free batch Nr 2500
They knew we used colour rods in our pieces, but the only source they knew about was the Murano cane so the average expansion coefficients at 10,10 (25-300) and 10,55 (25-400)
You can imagine that suddenly a whole different range of colours exploded.
The 2400 worked much better but who wants 2% lead out the chimney every melt.
It took a lot of time to convince them to steer the lead free more towards the German rods.
In the mean time GLASMA was started and again after initially producing exclusively for the factory's they started marketing a lead free pelletised batch.
We knew about Spruce-Pine but that was expensive and far away. Lots of sources for cullet in those days.
Still everybody experimented and knew what to expect most of the time. If it survives the diamant saw its OK.
Very low tech.

Originally posted by Pete VanderLaan I'm still trying to figure out "sideways".

It's good to know that glassworkers can be lazy on both sides of the Atlantic.

Sideways... as in the movie.... as in Pinot-obsessed freaks that rant on about stuff like...

"Um, it's a hard grape to grow, as you know. Right? It's uh, it's thin-skinned, temperamental, ripens early. It's, you know, it's not a survivor like Cabernet, which can just grow anywhere and uh, thrive even when it's neglected. No, Pinot needs constant care and attention. You know? And in fact it can only grow in these really specific, little, tucked away corners of the world. And, and only the most patient and nurturing of growers can do it, really. Only somebody who really takes the time to understand Pinot's potential can then coax it into its fullest expression. Then, I mean, oh its flavors, they're just the most haunting and brilliant and thrilling and subtle and... ancient on the planet. "

Ya know... like people get on this board about LECs.... over the edge.....

Ya know... like people get on this board about LECs.... over the edge.....

***************************
Ooooh... testy. Or maybe like some people get over the competition in the fused industry. It's all family, just some of it belongs in re-hab.

I have yet to see Sideways so it didn't click. I was way too busy with the Incredibles and the Jack Jack Attack. When I pointed out to my kids that they were a knock off of the fantastic four, they were very disappointed.

Lani, it wasn't as if we thought SP87 was a "standard", it was just a very large elephant in the room that was difficult to ignore. East Bay Regular batch played some part in our decisions as well.

Tom, I'd be curious to learn how Nick Labino came up with the expansion/viscosity characteristics of SP87 in the first place.
What was he comparing it to? I presume that he tested it against a selection of Kugler. That must have given him some headaches.

In some ways it was fortunate for us that SP87 had/has such market dominance in the States. Things are much more messy in Europe.

With the polarimeter we look for +/- 3 degrees. Trident seals mostly survive 10 degrees low and 15 degrees high which just goes to show how much glass blowers can get away with.

By the way, Gaffer offers a free trident seal testing facility for glass blowers who want to know where their own batch stands relative to our standard.

Originally posted by Pete VanderLaan **********************
One of the main reasons people really liked my black as an example was firstly the density of the color but also the fact that it does not bleed at all and stays absolutely where you put it. . It measures a 96.0 but has a close viscosity match to SP87 and still contains a substantial amount of lead.. It presents no strain in a ring test at all. I find bringing all of the gut features of a glass body to be very contradictory especially when one is trying to match up radically different formulations. I am thinking out loud here and will probably get an earful from someone.

do you think that it is tight because it is so reducing. John Curtis showed me a decorating trick that has a normaly soft lead oxidising color on top of a reducing clear or carbon amber or some sort of heavy reducing glass (Cu ruby). normally you can't make tight designs with, for instance, R144, but on a reducing glass it stays put. I think that is why r95 is so sloppy (heavy oxidising)and your black is tight.

Some 18 months ago I asked about the trident seal test, I got replies that I could not agree with. It is probably the most simple test for testing "compatability" of one glass against a standard, it is far easier than the ring test and infinately more accurate than the thread test.
It seems to me one can get one's recipe to within a point or three of where you want to be by using English and Turner's! Well within the ball park to use the Haggy Trident Seal test. Obviously one would have to choose a standard.
My guess is that there are't many glass blowers out there, especially the week end warriers, that could make an accurate ring to test.
All that is necessary is that you look at the Gaffer web site and send a piece of cane and Gaffer will test it free of charge now waht more could you ask.
This has been a very educational thread and I congratulate all who have given thoughtfull, intelegent input.

I don't know what all went into the decision making proscess that resulted in the Labino formula. We had another guy working for us at the time that did the talking with Nick.

In the early 80's, Nick gave a lecture at the Gas conference (I think the one in Toledo) pointing out how bad the glass was that the studio blowers were using. (I believe he focused on the problem of durability in the lecture.) This glass was primarily the cullet coming from the handglass factories. In addition, by the time he started working on the formula Nick had spent more than 20 years experimenting with various glasses with with the perspective of using them in the studio and for blowing. I'm sure he had lots of Kugler lying around as well. Before coming to Studio Glass, Nick was invoved in the fiberglass industry.

In addition, Nick gave us the formula in the form of a chemical analysis and the original formula did not include the lithium. We had to translate the chemical furmula into a list of materials. This would have changed some of the charateristics slightly and the later addition of the lithium would have also effected things. Then I think the actual coe that was arrived at for the 87 was more happenstance than design and more our work than his as we did some adjusting of the coe until we arrived at the 87. We were trying for something that fell within the range of variation (that is would fit) of the most popular Kugler colors (the transparents and the 61 white and black). We aso wanted it to melt as easily as possible without sacrificing too much fit.

We made another adjustment to come up with the 83 but the 83 never really took off in the marketplace.

We made another adjustment to come up with the 83 but the 83 never really took off in the marketplace.

*********************
which is worthy of note since the kugler opaques were (I believe) the target glasses the 83 was shooting at. The kugler opaques do not really fit the SP87 or any other commercial clear batch out there on either L.E.C. or viscosity or annealing curve or phase of the moon.

Gaffer's opaques ( and mine) were engineered to fit the current clear batches, but not the cullets.

In cullets we have:
Fenton C-4
Fenton C-6
Other Fentons
Seattle Batch CBG
Spectrum 96
CR LOO Something
Bullseye Clear
These are all over the map
and I'm sure I'm leaving some out. At Least DryKiln Crystal A is gone and so is Keystone cullet.

It gets far worse when you add in the european and australasian stuff.

Some of these have come and gone, Some new ones try to enter the market. Some, like Vermont Batch, never actually made a pound of batch.Most but not all are 96 glasses, which is why 96 is the elephant in the room. Almost all are terrible casting glasses which is tied to their formula structures.You are far luckier than you realize.

go ahead, be picky. I think the point is made anyway. If you actually can't remember the names, then there must be lots of them. If it is Gabbert, which I have no doubt that it is, I think there are fenton cullets as well. The more the merrier. I would think that Lani gets it by now.

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